Answer:
1.467 x 10^15 kg
Step-by-step explanation:
Length = 160 km
width = 40 km
height = 250 m
density = 917 kg/m^3
Volume = length x width x height
Volume = 160 x 1000 x 40 x 1000 x 250 = 1.6 x 10^12 m^3
Mass = Volume x density = 1.6 x 10^12 x 917 = 1467.2 x 10^12 kg
= 1.467 x 10^15 kg